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暴露在高蒸发速率环境下的新拌混凝土很容易产生塑性收缩裂缝,特别是表面积与体积的比率很大的时候,目前的研究都证明了,减少拌合水的表面张力是减少塑性裂缝的一种很有效的办法。我们将传统混凝土和高强混凝土掺加超塑化剂和减缩剂,在塑性阶段暴露干燥,测量毛细孔压、沉降、内部温度和蒸发速率,结果显示减缩剂对减少混凝土甚至是高强混凝土的塑性裂缝都是很有效的,这主要由于蒸发速率减少,原因是孔中弯液面的发展导致毛细管压的峰值出现延迟和较低的沉降率。
Fresh concrete exposed to high evaporation rates is prone to plastic shrinkage cracks, especially when the ratio of surface area to volume is high. Current studies have demonstrated that reducing the surface tension of the mixing water is one of the ways to reduce the plastic fracture A very effective way. We mixed traditional concrete and high-strength concrete with superplasticizers and shrinkage reducing agents, exposed them to dryness during the plastic phase, measured the pore pressure, sedimentation, internal temperature and evaporation rate. The results show that the shrinkage reducing agent can reduce the plastic cracks of concrete and even high-strength concrete Are all very effective, mainly due to the reduction in evaporation rate due to the development of meniscus in the well causing a delay in capillary pressure peaks and low settling rates.